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Feb. 4, 2011 -- People unlucky enough to suffer a painful shingles attack had one consolation: the belief it would never happen again.

Now that comforting belief has been shattered. A new study shows that shingles is at least as likely to strike a person who's already had one bout of the disease as one who has never had it.

In the eight years after a shingles outbreak, Olmstead Medical Center researcher Barbara P. Yawn, MD, and colleagues find, 6.2% of people come down with a second or even a third attack.

Recurrent attacks are known to happen in people with impaired immune systems, but 85% of recurrences are in people with normal immune function.

"And that's only within eight years," Yawn says in a news release. "As you continue to follow these patients throughout their lives, it's likely the recurrence rate will be much higher than 5 percent."

It seems unfair, but people whose initial shingles outbreak caused pain for 30 days or more had the greatest the odds of a second bout. This risk diminished three to four years after the initial attack.

Women are at higher risk than men. Their risk of recurrent shingles is 7.2%, vs. 4.5% for men. People aged 50 and older were at higher risk than younger adults.

Should More Get Shingles Vaccine?

Shingles is known to doctors as herpes zoster. It's caused by the varicella zoster virus. That virus causes varicella -- chickenpox -- the first time a person is infected.

But the virus doesn't go away when chickenpox is over. It hides in nerve roots. For reasons not entirely understood, the virus sometimes re-emerges from the nerve root and affects the skin, where it causes the painful lesions known as shingles.

"For many people, herpes zoster is not a once-in-a-lifetime event, demonstrating that having herpes zoster does not ensure protection against future herpes zoster episodes," Yawn and colleagues conclude.

The Yawn study enrolled 1,669 people age 22 or older who had shingles diagnosed between 1996 and 2001. They were followed for an average of 7.3 years, and for as long as 12 years.

"Our high herpes zoster recurrence rates suggest that zoster vaccination should be offered in people who have had a herpes zoster episode to prevent potential recurrences," Yawn and colleagues suggest.

The herpes zoster vaccine is recommended for adults age 60 and older. Yawn tells WebMD that she feels it should be recommended for people at age 50 but that it would not be cost-effective to vaccinate people at younger ages.

The Yawn study appears in the February issue of Mayo Clinic Proceedings.